1. Field of the Invention
The present invention relates to flexible extension shafts (see FIG. 1), a tool that permits a rotary drive device to impart rotary motion upon a distal tool bit by inserting one end of the flexible extension shaft into the collet of the rotary drive device, and by inserting the tool bit into the opposing end of the flexible extension shaft More particularly, the present invention provides a device that protects a user""s fingers when operating the flexible extension shaft irrespective of the position of the user""s hand upon the flexible extension shaft.
2. Background of the Prior Art
Flexible extension shafts come in a variety of sizes and configurations for the purpose of facilitating the transfer of rotary motion from a hand held rotary drive device to a tool bit that can only engage a preselected fastener if the tool bit is physically separated from the cumbersome rotary drive device. A person operates a flexible extension shaft by inserting a first end of the shaft into the collet of the drive device, inserting a preselected tool bit into the opposing end of the shaft, then holding the second end with the tool bit therein such that the tool bit engages a fastener while the person operates the drive device with his other hand to impart rotary motion upon the fastener. On occasion, the user must bend the shaft to achieve engagement between the tool bit and the fastener.
Referring to FIG. 1, the problem with bending the shaft and at the same time holding the second end of the shaft while the tool bit engages the fastener, is that the user""s fingers can be pinched between movable and rigid members 8 and 9 that form the second end of the shaft 10. More specifically, an outer end portion 58 of the movable member 8 snugly receives the tool bit (not pictured). A relatively smaller inner end portion 52 of the movable member 8 slidably inserts into a receiving end portion 50 of the rigid member 9. The movable member 8 is extended relative to the rigid member 9 when the shaft 10 is straight. The inner end portion 52 of the movable member 8 and the receiving end portion 50 of the rigid member 9 cooperate to form a recess 48 when the shaft is straight When the shaft is manipulated from a straight to a bent position, the movable member 8 is forcibly pulled into the rigid member 9 thereby disposing the relatively larger, knurled outer end portion 62 of the movable member 8 adjacent to the receiving end portion 50 of the rigid member 9 which could pinch a finger if the finger was positioned in the recess during the bending of the shaft 10.
A need exists for a device that will circumscribe the recess between the movable and rigid members irrespective of the position of the movable member relative to the rigid member to protect the user""s fingers irrespective of the position of the user""s hand upon the flexible extension shaft. Further, the device must not obstruct the operation of the shaft when the movable member is forcibly slid toward or away from the rigid member when the shaft is correspondingly bent or straightened.
It is an object of the present invention to overcome many of the disadvantages associated with manually operating a flexible extension shaft that transfers rotary motion from a drive tool to a tool bit.
A principle object of the present invention is to provide a device that protects a user""s fingers when operating a flexible extension shaft. A feature of the device is a deformable member that is circumferentially disposed about portions of movable and rigid members. An advantage of the device is that a user""s fingers will not be xe2x80x9cpinchedxe2x80x9d irrespective of hand placement upon the flexible extension shaft.
Another object of the present invention is to provide a device that does not interfere with the operation of the flexible extension shaft. A feature of the device is relatively small annular protuberance or xe2x80x9cbulgexe2x80x9d that is formed at a mid-portion of the deformable member, the bulge being disposed proximate to a recess formed when the movable member is extended relative to the rigid member. Another feature of the device is a relatively large annular bulge formed at the mid-portion of the deformable member when the movable member is slid toward the rigid member. An advantage of the device is that the mid-portion of the deformable member is prevented from being pinched between the movable and rigid members irrespective of the position of the movable member relative to the rigid member as the flexible extension shaft is manually manipulated to a bent position.
Still another object of the present invention is to provide a device that is relatively easy to secure to the flexible extension shaft. A feature of the device is cylindrical first and second end portions integrally joined to a mid-portion member to form the deformable member, the first and second end portions engaging cylindrical surface portions of corresponding rigid and movable members of the flexible extension shaft. An advantage of the device is that a clamp is capable of engaging the first end portion sufficiently tight to maintain the positions of the first and second end portions relative to the corresponding rigid and movable members.
Yet another object of the present invention is to provide a device that can be secured to the flexible extension shaft without using any banding or clamping means. A feature of the device is a recess in the inner wall of the first end portion. Another feature of the device is a knurled inner wall of the second end portion. An advantage of the device is that the recess in the inner wall engages a ridge on the surface of the rigid member thereby preventing the device from longitudinally moving upon the flexible extension shaft. Another advantage of the device is that the knurled inner wall of the second end portion cooperatively engages a knurled surface portion of the movable member thereby preventing the device from radially moving upon the flexible extension shaft.
Another object of the present invention is to provide an alternative device that protects a user""s fingers when operating an alternative flexible extension shaft. A feature of the alternative device is a bulge that is disposed closer to a first end portion than to a second end portion. Another feature of the alternative device is that the second end portion is secured to the rigid member via meshing knurled surfaces of the inner wall of the second end portion and the outer wall of the rigid member. An advantage of the alternative device is that the bulge prevents the user""s fingers from being pinched when a moving member of the flexible extension shaft is forcibly pulled into a rigid member of the shaft when the shaft is manually manipulated from a straight to a bent position. Another advantage of the alternative device is that the second end portion is capable of being secured by a band or clamp to the rigid member of the alternative flexible extension shaft without the first end portion being secured to the movable member thereby allowing a rounded portion of the movable member to be pulled into the rigid member while the first end portion and the bulge of the mid-portion member prevent the user""s fingers from being pinched irrespective of the position of the user""s hand upon the alternative flexible extension shaft.
Briefly, the invention provides a device for protecting a user""s fingers when operating a flexible extension shaft comprising a first end portion disposed upon a rigid member of the flexible extension shaft; an opposing second end portion cooperatively disposed upon a movable member of the flexible extension shaft; means for securing said first end portion to the rigid member; means for joining said first and second end portions whereby relative movement between the rigid member and the movable member of the flexible extension shaft is unobstructed by said joining means irrespective of the relative positions of the rigid member and the movable member; and means for preventing a user""s finger from being disposed between the rigid member and the movable member irrespective of the position of the user""s hand upon the flexible extension shaft.